It has been well documented in medical journals that the incidence of deep vein thrombosis (VT) can be significantly reduced by the use of devices for applying compressive pressure against a patient's legs. Thus, it is recognized that the velocity of blood flow in a patient's extremities, particularly the legs, markedly decreases during confinement. Such pooling or stasis of blood is particularly pronounced during surgery, immediately after surgery, and when the patient has been confined to bed for extended periods of time. It is also known that stasis of blood is a significant cause leading to the formation of thrombi in the patient's extremities, which thrombi may cause severe injury and even death.
The prevention of stasis by intermittent pneumatic compression of the legs is understood to be achieved by producing a high flow pulsatility that empties the veins periodically, cleaving not only the soleal sinuses and axial veins but also the valve sinuses in the axial veins.
The Kendall Company, assignee of the present invention, manufactures and sells under the trademarks "SCD" and "HomeRx" highly efficacious devices for applying compressive pressures to the legs. These devices include sleeves having multiple chambers which allow graded compression over the whole lower limb and which also allow the sequential application of pressures up the leg producing a wavelike milking action for optimum effect in preventing stasis.
The aforementioned commercial devices currently on the market utilize a conduit system in which four sets of conduits provide fluidized pressure from a controller to elongated inflatable sleeves around the legs. Specifically, one set of conduits provides compressive pressure to a chamber in the sleeve in the ankle region, a second set to a chamber in the calf region, a third set to a chamber in the thigh region, and a fourth set provides air for ventilating the chambers of the sleeve to cool the patient's leg.
Devices of the foregoing description utilizing four sets of conduits from a controller source of pressurized air in fluid communication with the sleeves are disclosed, for example, in U.S. Pat. No. 4,253,449 of Arkans et al and assigned to The Kendall Company, which patent will be discussed in more detail hereinafter.
In view of the commercial success of sequential compressive devices of this description over the years, it follows that many thousands of controllers for these four-conduit devices are currently found in hospitals and clinics throughout the United States as well as other countries where they are available.
Another system for applying compressive pressure to the limb utilizes what may be termed a "single conduit device" wherein air from the controller is transmitted by a single conduit to the ankle chamber of the sleeve and then from the ankle chamber where introduced into the sleeve successively upward to the calf and thigh chambers. Devices of this description utilizing a single conduit from the controller sources of air to the compression sleeve are disclosed, for example, in U.S. Pat. No. 4,029,087 issued to Dye et al and assigned to The Kendall Company, which patent will also be discussed in more detail hereinafter.
When single conduit devices such as those described in the aforementioned Dye et al patent subsequently become available, it will be extremely desirable to provide clinicians with the ability to utilize the controllers currently in house for use with both the multiconduit devices currently available and the single conduit devices as they subsequently become available.
Stated simply, the task of this invention is to devise means for making the controllers now available for devices for applying compressive pressure to the legs adaptable for use in both the current multiconduit systems and single conduit systems.